I don't want to see the timeline advanced: there is way too rich content of 998 to need more stuff to happen.
The 3e Campaign Setting is, in my opinion, the Eberron bible. The 4e campaign setting is nice, though any post in any thread on any site by Keith Baker (/Hellcow) is an amazing contribution. I don't need another Campaign Setting book.
I also want to see mechanical updates to: dragonmarks, changelings, kalashtar, artificers, lightning rails, etc.
I hope for a really good mega-adventure, with all the mechanics updates to run any Eberron adventure I might want. I don't need background or government structure on Breland or Aundair, or history of the giants/dalkaer/elves. I just want 5e stats for shifters, dragonshards, et al. And I want a really good adventure that reflects the setting.
Who here remembers the Dungeon magazine "Chimes at Midnight" Victor Saint-Demain trilogy? That, in one 256-page hardback.